1. Field of the Invention
The present invention concerns a thermostatic valve for a fluid circuit, including a thermostatic element of expansible material. It also concerns a heat engine associated with a cooling fluid circuit equipped with such a valve, and also a method for manufacturing such a valve.
2. Brief Description of the Related Art
In numerous applications of the field of fluidics, especially for the cooling of heat engines of vehicles, such valves are used for distributing a fluid entering by different circulation paths according to the temperature of the incoming fluid. In order to distribute the fluid according to other parameters, especially conditions outside the valve, such as ambient temperature or the load of the vehicle propelled by the engine equipped with the valve, it is known to provide means for electrical heating of the expansible material contained in the thermostatic element of the valve. It is then possible to control the actuation of the thermostatic element from outside the valve, independently of, or as a complement to the temperature of the incoming fluid, especially by means of an onboard computer in the vehicle, programmed accordingly.
It is however necessary to supply electricity to the heating means, such as a heating resistance, that are located in the expansible material of the thermostatic element, while the latter is at least partially immersed in the flow of fluid to be regulated by the valve.
In order partly to remedy this difficulty, it is known to arrange the heating resistance inside a piston of the thermostatic element, partially immersed in the expansible material and mounted so as to slide with respect to the body of the thermostatic element containing the material. By immobilising the piston with respect to the valve housing, supplying power to the resistance brings about the expansion of the material, thereby causing the body of the thermostatic element to slide round the fixed piston, a blocking means being carried by the body so as to act on the circulation of the fluid in the valve.
The arrangement of such a “heating piston” within the valve, as proposed in EP-A-0 853 267, is however complex to produce and raises problems of providing a tight seal, in particular in the area of electrical junction between the connection terminals of the heating piston, that are accessible from outside the housing, and an electric power supply element, such as a cable or the like.